A radio mobile communication system such as a mobile telephone system and a wireless LAN (Local Area Network) is in wide use today. In order to further improve communication speed and communication capacity in the field of radio mobile communication, continuous discussion is in progress on next-generation communication technology. For example, standardization of communication standards for LTE (Long Term Evolution), LTE-A (LTE-Advanced), etc. has been completed or is currently under study in the 3GPP (3rd Generation Partnership Project) which is an association for standardization.
In such a radio communication system, attention is being paid on a network called HetNet (Heterogeneous Network). For example, HetNet is a hierarchical network of a variety of cell sizes, including a macro cell, a pico cell, and a micro cell. In each cell, radio communication is carried out using different radio communication methods (such as LTE and 3G) with different frequency bands. By hierarchized cells, the HetNet can improve total capacity of a mobile communication system.
Meanwhile, in the radio communication system, there is a technique called handover (or handoff). Handover is a technique to perform radio communication while a terminal apparatus switches over a base station apparatus to be connected to. By the handover, the terminal apparatus can perform continuous radio communication.
As a technique related to such radio communication, there is a technique as described below, for example.
Namely, in a radio mobile communication system in which a hierarchical cell structure is adopted, there is a technique such that a mobile station apparatus selects a destination cell by comparing a predetermined time before the number of times of cell selection and/or cell reselection in a certain time reaches a certain value with a threshold, so as to be shifted to a standby state.
According to the above technique, for example, it is said that each mobile station apparatus can be placed in a cell area having an appropriate size according to a traveling speed and a cell structure.
Further, in a heterogeneous access system, there is a technique of observing service quality (QoS) measured by an access system currently in connection, to search and select an optimal access system for the service concerned when QoS falls down to a preset threshold or lower.
According to the above technique, for example, in a mobile network environment in which heterogeneous access systems are mixed, it is said that a method and an apparatus for selecting an optimal access system can be provided.
Furthermore, there is a technique for a communication control apparatus to control handover by a terminal apparatus, in which, for each cell identified by a cell ID included in a position information history, a cell ID that is not appropriate for the terminal apparatus to connect to is removed from the position information history.
According to the above technique, it is said that an order to switch over a cell to which the terminal apparatus is connected by handover can be optimized.